Cognition (also called cognitive science) began as a new haven for those who dared to speak of "mind" in an era when behaviorists had outlawed mind and favored description rather than explanation of behavior. This area, which had been dormant during the first half of the 20th century, was jump-started in the 1950's by new cooperation among psychologists, computer scientists, information theorists, physicists, mathematicians, and neuroscientists. Their common goal was to explain mental behavior symbolically and mechanistically, much as a computer algorithm is explained by the instructions that comprise it. No wonder cognition now covers a wide range of topics, from decision making and problem solving, to language production and understanding, to abstract concept formation and object categorization, and more recently to visual and other sensory aspects of cognition. With so many topics, it is no wonder that no one discipline dominates the process of mapping out such a vast and complex landscape. Cognitive scientists have marshalled an impressive array of theories that have not only shed light on these various cognitive process but have also sought to define the very nature of cognition itself.